Overview
Overview
FOXO4-DRI (also known as Proxofim) is a synthetic D-retro-inverso peptide designed to selectively induce apoptosis in senescent cells by disrupting the FOXO4–p53 protein interaction[1][2]. When this interaction is blocked, p53 translocates to the mitochondria in senescent cells, triggering their programmed death while sparing healthy cells[1]. This educational protocol presents a once-daily subcutaneous approach using a practical dilution for precise insulin-syringe measurements. Reconstitute:
- Category
- Longevity
- Routes
- subcutaneous
Mechanism
FOXO4-DRI
Mechanism of action
Mechanism of action
In plain English: senescent cells survive by holding the protein p53 hostage. They use another protein, FOXO4, to keep p53 stuck in the nucleus so it cannot trigger cell death. FOXO4-DRI acts as a decoy that competes with FOXO4 for p53. Once p53 is freed, it moves out of the nucleus toward the mitochondria and sets off the intrinsic apoptosis pathway (a caspase-driven self-destruct program). Healthy cells do not lean on the FOXO4-p53 link for survival, which is why the effect is reported as selective for senescent cells. This mechanism was first described in mice and cell cultures. A 2025 Nature Communications paper mapped the binding to the disordered transactivation domain of p53, adding structural detail to how FOXO4-DRI engages its target.
Key research findings
- 01
A synthetic D-retro-inverso (DRI) peptide designed to disrupt the FOXO4-p53 protein interaction; studied as a senolytic research tool that selectively triggers p53-dependent apoptosis in senescent cells (cell-based studies).
- 02
Animal model: in a widely cited 2017 study (Baar et al., Cell), the peptide was reported to selectively target senescent cells and to improve markers of fitness, fur density, and renal function in aged and in chemotoxicity/progeroid mouse models.
- 03
Reported preferential activity in senescent versus proliferating cells in vitro is a central feature of its research interest.
- 04
No human clinical trials; it remains an experimental research compound.
- 05
The D-retro-inverso design is intended to increase peptide stability against proteolysis (a research-chemistry rationale, demonstrated in models).
Primary source: Foundational mouse study (Baar et al., 2017, Cell): Designed FOXO4-DRI and showed selective senescent-cell clearance, with restored fitness, fur density, and kidney function in aged and chemotherapy-treated mice. Leydig cell aging (Zhang et al., 2020, Aging): FOXO4-DRI improved testosterone secretion and the testicular microenvironment in aged mice by clearing senescent Leydig cells. Human chondrocytes in vitro (Huang/Zhu et al., 2021): Selectively removed senescent cells from expanded human chondrocyte cultures, suggesting cartilage-repair relevance — in a dish, not a person. Endothelial senescence (2025, PMC): Reported FOXO4-DRI clearing senescent endothelial cells via a p53/BCL-2/caspase-3 pathway in animal and cell models. Mechanism mapping (Nature Communications, 2025): Identified the disordered p53 transactivation domain as the binding target, adding structural detail to the mechanism.
Researched Effects
Researched benefits
Areas of active research and investigation. Results may vary and are based on preclinical or early clinical data.
Promotes selective clearance of senescent cells in various tissues, including aged organs and pathological conditions[3][4][5].
Animal studies show improvements in tissue regeneration, reduced inflammation, and enhanced organ function following senescent cell clearance[3][5].
In aged mice, FOXO4-DRI treatment improved testosterone levels and markers of cellular health[3].
No human clinical safety or efficacy data currently exist[6]; tolerability in humans remains uncharacterized.
Protocol Reference
Protocol reference
Commonly cited research range: 250–500 mcg, daily.
Reference figures reported in the research literature — not a dosing recommendation. For interactive vial math and scheduling, see the Calculator and Schedule tabs.
Cited protocol & reconstitution guide
Source-backed reference fields by phase, including any volume fields authored in the cited guide.
Weeks 1–4
250 mcg
Weeks 5–8
375 mcg
Weeks 9–12
500 mcg
Weeks 13–16
500 mcg
| Phase | Reference amount | Units / volume |
|---|---|---|
| Weeks 1–4 | 250 mcg | 7.5 units (0.07 mL) |
| Weeks 5–8 | 375 mcg | 11.2 units (0.11 mL) |
| Weeks 9–12 | 500 mcg | 15 units (0.15 mL) |
| Weeks 13–16 | 500 mcg | 15 units (0.15 mL) |
Titration protocol
- Weeks 1–4Start250 mcg
Daily SubQ; 7.5 units (0.075 mL) at 10 mg + 3.0 mL. About 7 mg used over the block.
- Weeks 5–8Build375 mcg
Daily SubQ; 11.25 units (0.1125 mL) at 10 mg + 3.0 mL. About 10.5 mg used over the block.
- Weeks 9–12Build500 mcg
Daily SubQ; 15 units (0.15 mL) at 10 mg + 3.0 mL. About 14 mg used over the block.
- Weeks 13–16Maintenance500 mcg
Daily SubQ; 15 units (0.15 mL) at 10 mg + 3.0 mL. About 14 mg used over the block; full 16-week ladder uses about 45.5 mg total.
Storage & Handling
Storage requirements(typical for most peptides)
Can be stored for extended periods. Protect from moisture.
Store in refrigerator door. Never freeze after reconstitution.
Label vials with reconstitution date. Discard if cloudy.
Reconstitution steps
- 01🌡️Sanitize — wipe the vial stopper and BAC water stopper with separate alcohol swabs.
- 02🧴Draw 3 mL bacteriostatic water into a sterile syringe — this 10 mg vial yields 3.33 mg/mL.
- 03💉Add slowly — aim the water down the inside wall of the vial, not directly onto the powder.
- 04💧Do not shake — swirl gently and let the powder dissolve; shaking can damage the peptide.
- 05🔄Inspect — the solution should look clear; discard if cloudy or full of particles.
- 06🏷️Label — write the date on the vial so you can track freshness.
- 07❄️Refrigerate at 2–8 °C (35.6–46.4 °F) and use within a short window; do not reconstitute more than will be used promptly.
- 08💉Important: This guide is for educational purposes only and is not medical advice. For research use only. Not for human consumption.
Additional storage notes
Store at −20 °C (−4 °F) or below in dry, dark conditions; minimize moisture exposure [8] .
Refrigerate at 2–8 °C (35.6–46.4 °F); use within 1 month when using bacteriostatic water [8] .
Allow vials to reach room temperature before opening to reduce condensation uptake.
If long-term storage of reconstituted solution is needed, aliquot into single-use vials and freeze to minimize degradation [8] .
Clinical Evidence
Clinical evidence
Preclinical mouse studies report selective clearance of senescent cells and improvements in markers of aging; human data are absent.
Foundational mouse study (Baar et al., 2017, Cell): Designed FOXO4-DRI and showed selective senescent-cell clearance, with restored fitness, fur density, and kidney function in aged and chemotherapy-treated mice. Leydig cell aging (Zhang et al., 2020, Aging): FOXO4-DRI improved testosterone secretion and the testicular microenvironment in aged mice by clearing senescent Leydig cells. Human chondrocytes in vitro (Huang/Zhu et al., 2021): Selectively removed senescent cells from expanded human chondrocyte cultures, suggesting cartilage-repair relevance — in a dish, not a person. Endothelial senescence (2025, PMC): Reported FOXO4-DRI clearing senescent endothelial cells via a p53/BCL-2/caspase-3 pathway in animal and cell models. Mechanism mapping (Nature Communications, 2025): Identified the disordered p53 transactivation domain as the binding target, adding structural detail to the mechanism.
- 01A synthetic D-retro-inverso (DRI) peptide designed to disrupt the FOXO4-p53 protein interaction; studied as a senolytic research tool that selectively triggers p53-dependent apoptosis in senescent cells (cell-based studies).
- 02Animal model: in a widely cited 2017 study (Baar et al., Cell), the peptide was reported to selectively target senescent cells and to improve markers of fitness, fur density, and renal function in aged and in chemotoxicity/progeroid mouse models.
- 03Reported preferential activity in senescent versus proliferating cells in vitro is a central feature of its research interest.
- 04No human clinical trials; it remains an experimental research compound.
- 05The D-retro-inverso design is intended to increase peptide stability against proteolysis (a research-chemistry rationale, demonstrated in models).
Evidence maturity varies by compound; much peptide research is preclinical (in vitro or animal-model). Where human data are limited, findings should be read as research observations, not clinical conclusions.
References
Literature references
Published research articles and sources related to FOXO4-DRI.
- 01Nature Communications Biology — FOXO4-DRI induces keloid senescent fibroblast apoptosis by promoting nuclear exclusion of upregulated p53-serine 15 phosphorylation View Source
- 02Nature Cell — Targeted apoptosis of senescent cells restores tissue homeostasis in response to chemotoxicity and aging (original FOXO4-DRI discovery) View Source
- 03Aging (Albany NY) — FOXO4-DRI alleviates age-related testosterone secretion insufficiency by targeting senescent Leydig cells in aged mice View Source
- 04Journal of Cellular and Molecular Medicine — FOXO4 peptide targets myofibroblast ameliorates bleomycin-induced pulmonary fibrosis in mice View Source
- 05Cell — Clearance of senescent cells by ABT263 rejuvenates aged hematopoietic stem cells in mice (senolytic mechanism context) View Source
- 06Aging (Albany NY) — Methods & Protocols — FOXO4-DRI safety note: no human clinical dosing data exist yet View Source
- 07PubMed — A liquid chromatography high-resolution mass spectrometry in vitro assay to assess metabolism at the injection site of subcutaneously administered therapeutic peptides View Source
- 08Bachem — Care and Handling of Peptides (storage, reconstitution, stability guidance) View Source
- 09MedlinePlus — Subcutaneous (SQ) injections: technique, site selection, and safety View Source
- 10American Diabetes Association — Insulin injection site rotation and lipohypertrophy prevention View Source
- 11CDC — Vaccine administration: subcutaneous route (angle, site; no aspiration) View Source
- 12CDC (Subcutaneous Injection PDF) — Technique diagram and site guidance for subcutaneous injections View Source
- 13NCBI Bookshelf — Best practices for injection (asepsis, preparation, and administration) View Source
- 14PMC — Subcutaneous Drug Injection Review: pharmacologic considerations of the subcutaneous route View Source
- 15Pure Lab Peptides — FOXO4-DRI (10 mg) product page (quality and batch documentation) View Source
Observed Effects
Observed effects in cited research
Theoretical and reported concerns
- Off-target cell death: no compound is perfectly selective, so healthy cells with temporarily high FOXO4 could be affected in theory.
- Immune or clearance burden: a rapid wave of dying cells must be cleared, which could stress the system.
- Impaired healing: senescent cells help wound repair, so clearing them at the wrong time may not be wanted.
- Injection-site issues: redness, swelling, or irritation are common to any SubQ injection and are made worse by poor technique or low-quality product.
- Product quality is its own risk. As a D-amino acid peptide, FOXO4-DRI is costly to synthesize, and a wrong amino acid at the binding site can sharply cut activity. Unverified material may not contain what the label claims.
Research Considerations
Research considerations
Research Use Only - not for human or veterinary therapeutic use. Evidence is strictly preclinical (cell and/or animal models); it is a research compound, not a therapy, and has not been evaluated for human safety. Consult a licensed healthcare professional for any clinical decisions.
- Anyone with active cancer or undergoing cancer treatment — p53 and senescence pathways interact with tumor biology in complex ways.
- Pregnancy and breastfeeding — no data exist, and apoptosis-inducing agents are a clear unknown.
- Active infection, recent surgery, or wound healing — senescent cells assist tissue repair, so clearing them could theoretically interfere.
- Anyone who is immunocompromised — clearance of dying cells depends on immune function.
Factors noted in the research literature; not patient-specific medical advice.
Regulatory Status
Regulatory status
RUO
Comparisons
Comparisons
| Compound | Mechanism | Route | Status |
|---|---|---|---|
| FOXO4-DRIthis | A D-retro-inverso peptide designed to disrupt the FOXO4-p53 interaction in senescent cells, releasing p53 to selectively induce apoptosis of senescent cells (a senolytic mechanism). | subcutaneous | Investigational / RUO |
| Glutathione | An endogenous tripeptide (gamma-L-glutamyl-L-cysteinyl-glycine) functioning as a major intracellular antioxidant and redox buffer, supporting phase-II detoxification conjugation and neutralization of reactive oxygen species. | subcutaneous | Investigational / RUO |
| Livagen | A synthetic tetrapeptide bioregulator (Lys-Glu-Asp-Ala) studied for peptidase modulation and epigenetic/chromatin effects (e.g., heterochromatin decondensation) in aging cell models. | subcutaneous | Investigational / RUO |
| NAD+ | An essential coenzyme central to cellular energy metabolism (redox reactions) and mitochondrial function, and a substrate for sirtuins and PARPs in DNA-repair and signaling pathways. | subcutaneous | Investigational / RUO |
| Prostamax | A synthetic tetrapeptide bioregulator (Lys-Glu-Asp-Pro) derived from prostate peptide-complex research, studied for tissue-specific regulatory effects on prostate tissue. | intramuscular | Investigational / RUO |
| GHK-Cu | Stimulates collagen and glycosaminoglycan synthesis, promotes angiogenesis, and acts as antioxidant and anti-inflammatory agent. | subcutaneous, topical | Investigational / RUO |
| GHRP-2 | A synthetic hexapeptide that activates the ghrelin/GHS receptor (GHS-R1a) to stimulate dose-dependent growth hormone release; it also mildly engages prolactin and cortisol pathways. | subcutaneous | Investigational / RUO |
Attributes shown for research comparison only; not a statement of efficacy or therapeutic equivalence.
FAQ
Frequently asked questions
FOXO4-DRI is a synthetic D-retro-inverso peptide studied as a senolytic, meaning it is designed to selectively clear senescent cells. It works by disrupting the FOXO4-p53 interaction so that p53 can trigger apoptosis in those cells. It is also written FOX04-DRI and sold by some vendors as Proxofim.
It is investigated mainly for cellular senescence and aging. Mouse and cell studies have looked at clearing senescent cells in aged tissue, testosterone-producing Leydig cells, cartilage chondrocytes, and blood-vessel endothelial cells. All current uses are preclinical research contexts, not approved treatments.
The only published dosing protocol is from mouse studies: 5 mg/kg by intraperitoneal injection, given intermittently over weeks. No human dose has been established and no human trials exist. Community sources report a 16-week subcutaneous ladder of 250 mcg daily for Weeks 1-4, 375 mcg daily for Weeks 5-8, and 500 mcg daily for Weeks 9-16, but this is reported research context, not a recommendation.
Adding 3.0 mL of bacteriostatic water to a 10 mg vial gives about 3.33 mg/mL. On a U-100 insulin syringe, 7.5 units is about 250 mcg, 11.25 units is about 375 mcg, 15 units is about 500 mcg, and 30 units is about 1 mg. Use the calculator at peppal.app/calculator for other vial sizes.
Yes, this guide includes a community-derived 16-week daily dosing ladder and a reconstitution chart for a 10 mg vial reconstituted with 3.0 mL of BAC water. It converts syringe units into micrograms and milligrams. Any chart is a research reference only, since no human dose has been validated.
There are no documented human observed effects because it has not been tested in people. Theoretical concerns include off-target cell death, immune burden from clearing many cells at once, impaired wound healing, and injection-site irritation. Product quality is a separate risk with this expensive-to-make peptide.
No. As of June 2026 there are no completed or registered human clinical trials for FOXO4-DRI. All evidence comes from mouse models and cell cultures. ClinicalTrials.gov is the authoritative place to check if that ever changes.
FOXO4-DRI is not FDA approved and has no approved human indication. It is sold only as a research-use-only chemical and is not intended for human consumption. Laws vary by region, so verify local rules before purchasing.
FOXO4-DRI is a D-retro-inverso peptide built from a FOXO4 fragment that binds p53, joined to a cell-penetrating sequence, with a molecular weight near 4.8 kDa. Published descriptions vary slightly in reported length, so for the exact chemical identity check the PubChem entry rather than relying on a single secondary source.
Proxofim is a name used by some research vendors for FOXO4-DRI. It refers to the same senolytic peptide. Listings sometimes appear as Proxofim 10 mg.
No such claim can be made. Some preclinical work explores FOXO4-p53-targeting peptides against senescent cancer cells, and the developer has discussed cancer as a research interest, but there is no human evidence that FOXO4-DRI treats cancer. People with active cancer should be especially cautious.
No. This is an educational research reference about FOXO4-DRI, not medical advice or a treatment plan. Talk with a qualified clinician before making decisions about any unapproved research compound.
Research-use notice
Research Use Only. This educational content and calculation support is intended for private research documentation. It does not provide medical advice, human-use directions, or claims of safety or effectiveness.